Experimental Investigation Of Seepage And Solute Transport In A Disc Fracture Network

In order to investigate the seepage characteristics and solute transport of the fractured rock mass and fracture intersection in Karst Area,based on the 3D model theory of disc fracture,an experimental device consisting of 31 smaller disk cracks and 3 thick fractures were established,and an experimental study on seepage and solute transport under different hydraulic gradients was also conducted.The results showed that in the seepage experiment using disk fracture network physical model,the flow regime changed from transition flow to turbulence,and the power of hydraulic gradient was 0.5?1,and the statistical relationship between osmotic flow(V)and hydraulic gradient(J)could be well described by the nonlinear equation of motion V=312.32J0.77.Similar to that in the porous media,water head distribution decreases with the direction of hydraulic gradient.However,due to the existence of large fracture and the occurrence of fracture network,the direction of seepage in the fracture network was inconsistent with the direction of the total seepage,and the head distribution showed that the water head at some points was higher than that near the upstream.The solute breakthrough curve was the same as that in porous media,but in the early stage it was fluctuated,and the concentrations of some special points were higher than that of constant source when it kept stable.In the initial stage,the fluctuation of the breakthrough curve of each monitoring point was weakened along the flow path of the stationary source,and the fluctuation degree of the breakthrough curve in the same monitoring point increased with the decline of head difference.The experimental results can further deepen the understanding of seepage characteristics and the law of solute transport under the combination of fracture network and large fracture in Karst Area,which was theoretically and practically important to rational exploitation of fissure water and karst water resources as well as prevention and control of groundwater contamination.